After a well has been in operation for a number of years, the rate of production of oil or other fluids from the well may decrease to a point at which further operation of the well is not economically practical. Under these circumstances, various expedients have been proposed and utilized for enhancing the production and extending the life of the well. One system employed is to drill one or more drain holes laterally from the well into the surrounding earth formation to enable flow of oil or other fluids through those holes into the main well bore and through that bore to the surface of the earth. However, the drilling of laterally extending holes by conventional methods is relatively expensive and may not be warranted in many marginal wells.
Lateral holes may be formed by positioing in a well a whipstock having a deflecting surface engageable with a drill bit or drilling unit to direct that unit laterally from the main well bore into the earth formation. Such a whipstock may be lowered into the well with the drilling unit, and may have an anchor at its lower end for locking the whipstock in place, with the whipstock being attached to the drilling unit by a shear connection which can be broken in the well to allow the drilling unit to move past and be deflected by the whipstock.